Calibration and Accuracy Check System

ABSTRACT

Calibration and accuracy check systems for a chemical sniffer, such as a breath alcohol tester, which utilize the dispensing of droplets with determinable concentration of alcohol and/or other liquids in a determinable number either directly to a reaction chamber, or into a carrier gas which can be sampled. The systems generally provide for accurate sample concentration being provided to the breath tester while also providing for a simplified system which can be easier to move, and require less operational complexity, than prior wet or dry calibrating systems.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a Divisional of U.S. Utility patent application Ser.No. 13/688,943, filed Nov. 29, 2012, which is in turn a Continuation ofU.S. Utility patent application Ser. No. 12/397,206, filed Mar. 3, 2009,now U.S. Pat. No. 8,418,523, which in turn claims the benefit of U.S.Provisional Patent Application Ser. No. 61/033,218, filed Mar. 3, 2008and the benefit of U.S. Provisional Patent Application Ser. No.61/050,823 filed May 6, 2008. The entire disclosure of all thesedocuments is herein incorporated by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to systems and methods for providingcalibration and accuracy checking for a breath tester. Specifically,utilizing small dispersed drops of alcohol or a water and alcohol mix tosimulate exhausted human breath to a breath tester.

2. Description of the Related Art

For the purposes of public safety on the roads and elsewhere, there is aneed to make sure that individuals are not operating potentiallydangerous machines (such as automobiles) while they are impaired by theeffects of alcohol consumption. To try and prevent people from drivingdrunk, most states have enacted laws which impose fines or othercriminal penalties if individuals have a breath or blood alcohol levelabove a certain amount. In order to effectively enforce these laws, itis necessary to be able to measure the alcohol concentration in humanbreath and compare the results against legal limits. There are a varietyof measuring instruments used for determining the concentration ofalcohol in human breath ranging from small hand held devices to largerbench top units and machines built into cars or certain machinery. Sincea determination of breath alcohol above the legal threshold can resultin criminal penalties, loss of a job, or other sanctions, the accuracyof these instruments is paramount.

Great care and effort is taken by owners and managers of evidentialbreath testing equipment to ensure proper calibration as well asfollow-up accuracy checks at generally regular intervals. In attempts toeliminate the labor time of this testing and concerns about human errorin the testing, manufacturers of breath testing equipment often offerautomated or semi-automated methods for doing calibrations and accuracychecks. Some users of breath alcohol test equipment, such as MotorVehicle Law Enforcement, may even require an automatic accuracy checkevery time they test a human subject and sometimes even before and afterthe human subject test simply to make sure that the device is readingcorrectly and will supply court-admissible evidence.

There are generally different standards used when calibrating breathtesters. As breath (containing alcohol or not) is a vapor comprisingexhalation gases and vaporized substances, instruments that measurealcohol concentration in this breath vapor generally need standards tobe provided in a similar form for accurate calibration. Calibrationgases of many sorts are well known in many applications including breathtesting. In breath testing, the calibration standards are generally oftwo types, wet and dry. Wet standards include water vapor; dry standardsdo not. Some argue that wet standards are better because they includemoisture like human breath and are therefore more representative.However, commercial providers of both wet and dry standards generallyadvertise +/−2% accuracy of calculations with actual breath.

In either case, the alcohol concentration of measurement interest is ina carrier gas such as air, breath, or nitrogen. A typical breath ethanolconcentration which would result in illegal driving in most states is200 parts per million (ppm) or more. That is 200 parts ethanol permillion parts of carrier gas regardless of the carrier gas composition.Therefore, the standards generally provide samples which contain veryclose to 200 ppm to make sure the dividing line is correctly calibrated.

Wet standards have a long history in breath testing, are well accepted,and the liquids used in them can be certified by chemical analysisagainst NIST traceable standards. The standards are prepared bycombining known amounts of ethanol and water in a partially filled jarthat is accurately heated to 34° C. These heated jars are soldcommercially and are referred to as Simulators. At equilibrium, thequiescent headspace above the jar contains a vapor with a knownconcentration of ethanol along with nearly 100% relative humidity atthat temperature.

By introducing sober human breath or air from another suitable sourceinto the jar (by blowing or injecting gas into the liquid) the knownconcentration of ethanol vapor exits the headspace and can be introducedinto a breath tester at which point a measurement may be taken.

Dry standards, by contrast, have no water vapor included with them. Thisis because dry standards are prepared with carrier gases such asnitrogen or argon and are supplied in pressurized tanks ranging from500-2500 psi. At these pressures, if water vapor were included inamounts similar to human breath concentrations in practical field use,the water would condense out of the gas, trap ethanol, and cause whollyinaccurate results. The dry gas standards are typically certified bymeasurement against NIST-prepared standards.

In automated wet testing, the above-mentioned Simulators generally haveinput and output ports. Typically, a Simulator will sit alongside abreath test machine, normally on a desktop. The output of the Simulatoris plumbed into the instrument such that when gas is pumped into theSimulator input (either from a tester blowing into it, or from anassociated gas tank or pump), a vapor of known ethanol concentrationwill be presented for measurement or calibration in the same mannerhuman breath would be. Typically, an electric pump is used to pumpambient air into the Simulator for this purpose. The pump may beinternal to the breath tester, part of the Simulator itself, or anentirely separate component. Typically, gas is pumped through aSimulator for 4-10 seconds in order for a measurement to be completed.This pump time varies depending on the flow rate and the amount ofinstrument volume that has to be purged of ambient gas before ameasurement is taken to ensure the measurement is taken of the carriergas with the correct concentration of ethanol.

Every time a sample is taken from a Simulator, some of the ethanol inthe liquid replenishes lost ethanol from the headspace. However, overtime, the equilibrium concentration of ethanol provided by the Simulatordecreases from its originally intended value as ethanol is slowly lostto the ambient air due to the carrier gas (and the carried ethanol)being exhausted from the breath tester. Some breath test instruments userecirculation systems that take the ethanol vapor provided by theSimulator output, after it exits the breath tester's measurementchamber, or manifold, and pumps it back into the Simulator inlet,instead of using ambient air to provide the simulated exhalation. Thisgreatly reduces any effects of lost ethanol from the Simulator causinglower concentrations to be provided over time since used ethanol is notexhausted to the ambient, but is returned to the Simulator.

Whether using recirculation systems or not, care must be taken to avoidany condensation of water from the Simulator output until theconcentration of ethanol is measured by the breath tester. Otherwise,the alcohol in the gas will be less than intended due to ethanol beingcondensed from the gas. To avoid condensation, various elements or tubesin the instrument are generally heated prior to measurement.

It must be noted that the using Simulators for portable instruments orin on-site calibration tests can be problematic. They are subject tosplashing, tipping over, and operate properly within a very limitedambient temperature range due to their complicated design which isnecessary for accuracy. Further, they are not really designed for easyor efficient transport, and that tends to limit their use to controlledsettings.

The dry gas standards are provided in a variety of types ofhigh-pressure cylinders. A typical size of a tank is approximately 1liter or more. These cylinders are typically equipped with pressureregulators where the high tank pressure is regulated down to a muchlower delivery pressure to the breath tester to better simulate thepressure provided by human breath. Often, an electronic shut-off valvewill allow delivery of the low-pressure calibration gas to themeasurement chamber on demand.

Compared to wet standards, the dry standards offer some advantages. Drygas delivery systems generally represent a less complex system hardwaredesign to provide automated calibrations and accuracy checks than thewet standards. The dry gas system is generally easier for instrumentowners to manage and maintain and the dry gas system is certainly moreamenable to a portable system. Specifically, since the only majorcomponents of a dry gas system are the tank and regulator, they arepretty easily portable and are not as affected by movement or situationas wet systems. The dry gas tanks will eventually run empty, but norecirculation system is required to keep the value stable throughout thetank's lifetime.

However, dry gas standards have several factors that complicate theiruse. First of all, they require a compensation for barometric pressurein the breath tester. The concentration of dry gas standards follow theideal gas law, and the measured value will change with barometricpressure changes due to elevation or weather. Also, if a dry gas systemhas a leak, it is possible to lose a significant amount of gas before aproblem is noticed. Furthermore, some users (especially mobile ones)have concerns about the safety of transporting even relatively smallhigh-pressure gas tanks which, even while filled with generallynonflammable gas, are potentially explosive due to their high pressure.Lastly, as stated earlier, the dry gas contains no water vapor. Some whoare skilled in the art believe that a water component to the calibrationgas is essential, because water vapor is a large constituent of humanbreath and it would therefore be possible to challenge the reading of abreath tester which has only been calibrated using a dry gas system.

SUMMARY

Because of these and other problems in the art, described herein is acalibration and accuracy check system for use with a breath tester.These systems and methods can overcome some or all of the problemsinherent in both the wet and dry gas standard systems currently used inthe breath tester industry by utilizing a liquid water and alcohol mixsimilar to that used in a wet simulator, which would be NIST traceable,but which is provided in a generally sealed storage bottle. This mixtureis then dispensed as a series of specifically sized small droplets whichcan be counted to determine the exact composition injected. In anembodiment, this dispensing utilizes a dispensing nozzle and theamplification of induced capillary waves on the fluid to provide fordispersing of a specific number of regularly sized droplets.Essentially, this is the same general dispensing method as is used fordispensing ink in an inkjet print head. Using such a dispensing system,minute drops of this liquid are directly dispensed into an instrumentmeasurement chamber on demand for calibration and accuracy checkrequirements without need of a carrier gas, or are accurately dispensedinto a carrier gas for testing using the standard breath collectingapparatus of the breath tester.

There is described herein, among other things, a calibration system fora breath tester comprising: a storage reservoir containing a mixture ofwater and an alcohol at known concentration; a dispensing head fordispensing said mixture, said dispensing head including: a nozzle forejecting said mixture from said storage reservoir; and means foramplifying induced capillary waves into said mixture; wherein saiddispensing head can inject said mixture into a reaction chamber of saidbreath tester.

In an embodiment of the system said means for amplifying comprises aheating element or a piezoelectric element.

In an embodiment of the system, said alcohol comprises ethanol ormethanol.

In an embodiment of the system said dispensing head may be connecteddirectly to said reaction chamber or may dispense said mixture into acarrier gas.

There is also described herein, a calibration system for a breath testercomprising: a storage reservoir containing alcohol; a dispensing headfor dispensing droplets of known size from said storage reservoir; and amonitoring system for determining the number of droplets dispensed fromsaid dispensing head; wherein said dispensing head dispenses a fixednumber of droplets to said breath tester and said breath tester iscalibrated based on the resulting concentration of alcohol is based onsaid fixed number of drops dispensed.

In an embodiment of the calibration system said fixed number of dropletsmay be dispensed directly to a reaction chamber in said breath tester ormay be dispensed into a carrier gas which is then supplied to saidbreath tester.

In an embodiment of the calibration system the fixed number of dropletsmay change between successive tests or may change according to a patternover time.

In an embodiment of the calibration system said storage reservoir alsoincludes water.

In another embodiment of the calibration system the alcohol comprisesethanol or methanol.

There is also described herein, a method of calibration of a breathtester, the method comprising: providing a storage reservoir containingalcohol internal to a breath tester; dispensing a preselected number ofdroplets of known size from said storage reservoir to said breathtester; determining the breath alcohol level said preselected number ofdroplets represents; and calibrating said breath tester based on theresulting concentration of alcohol.

In an embodiment of the method, the droplets may be dispensed directlyto a reaction chamber in said breath tester.

In an embodiment of the method, the storage reservoir also includeswater.

In another embodiment of the method, the alcohol may comprise ethanol ormethanol.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B provide for a prior art fuel cell sampling system in topview (FIG. 1A) and sectioned side view (FIG. 1B).

FIGS. 2A, 2B and 2C provide a simplified sectioned side view of thesampling piston portion of the fuel cell sampling system of FIG. 1 inthree different positions. A ready or down position (FIG. 2A), theenergized sampling position (FIG. 2B), and an up position where thesample is in the reaction chamber (FIG. 2C).

FIG. 3 provides the sectioned side view of FIG. 1 enlarged withcomponent labeling.

FIG. 4 shows how to utilize a dispersed fluid jet to provide vaporsimulative of breath directly to a fuel cell reaction chamber.

FIG. 5 provides an embodiment of a calibration system using a dispersedfluid jet with a carrier gas.

FIG. 6 provides an embodiment of a discrete breath tester used incombination with the calibration system of FIG. 5.

FIG. 7 provides an embodiment of a continuous breath tester incombination with the calibration system of FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENT(S)

Due to the problems inherent in both the wet and dry gas standardsystems currently used in the breath tester industry, there is describedherein a calibration and accuracy check system that utilizes liquidalcohol, or a liquid water and alcohol mix similar to that used in a wetsimulator, which would be NIST traceable but is provided in a sealedreservoir. This mixture is then dispensed in a series of evenly sizeddroplets. Using such a dispensing system, minute drops of this liquidmay be dispensed directly into the reaction chamber of the breath testerfor calibration and accuracy check requirements. This testing can beperformed on-demand and under virtually any conditions. The requiredamount of alcohol is introduced to the measurement chamber withoutneeding to use a carrier gas, although one may be used in an alternativeembodiment. Even though the alcohol could be pure, it will generally bediluted with liquid such as water or other liquid components of humanbreath to provide for generally better repeatability of results and tobetter simulate human breath.

In an embodiment, when a sample (such as breath or calibration gas) isintroduced into a fuel cell or other measurement chamber, the sampletypically undergoes a chemical reaction such as, but not limited to, acatalytic reaction and electrons are given off in proportion to thealcohol concentration so long as the sample size is fixed. FIG. 1provides an example of a prior art fuel cell sampling system (100) andwould be common in an alcohol breath tester of current known design.This particular sampling system (100) is not meant to define the onlytype of sampling system with which the calibration and accuracy testingsystems and methods discussed herein may be used, but is meant to simplyillustrate one exemplary embodiment. In the embodiment of FIG. 1, thereis a top view provided as FIG. 1A and a sectioned side-view as FIG. 1B.A simplified and sectioned schematic view of the mechanism is shown inFIG. 2 in three different positions (FIG. 2A, FIG. 2B and FIG. 2C) whichshow the sampling operation of obtaining a sample from an associatedmanifold and placing it in the reaction chamber (133) for testing. InFIG. 3, the sectioned side view of FIG. 1 at the position of FIG. 2C isenlarged and shown with additional components. These FIGS will all bediscussed together.

The primary movement of the sampling system (100) is a centrally locatedpiston (101) which moves up against an upper stop (103) and down againsta lower stop (105). When the piston (101) is in the down position asshown in FIG. 2A, the sampling mechanism is cocked. The bi-stable springmechanism (111) at the top of the piston (101) is at rest with one ofthe arms (113) resting on the edge of a spring-loaded armature (115)next to an electromagnetic coil. This is the pre-testing state. When thecoil is energized, the armature (115) moves towards the coil (to theright in the FIG.) and the lever arm (113) is released as shown in FIG.2B, which provides for a sample to be pulled from the inlet (131) intothe sample chamber. The springs (111), in turn, pull the piston (101) upagainst the upper stop (103) as shown in FIG. 2C, which has now had anentire sample placed in the reaction chamber (133) and is ready tocommence testing of the sample.

FIG. 3 shows that the piston (101) is in turn connected to the top of adiaphragm (121), anchored at its periphery (123). When the piston (101)goes up, the center of the diaphragm (121) is pulled up creating avacuum and a gas sample is sucked in through the sample inlet (131)(generally from a breach manifold or other collection system) into a gasreaction chamber (133) between the diaphragm and the face of a fuel cell(135). The time for the sampling to occur is generally a fraction of asecond. In a standard fuel cell testing embodiment, the entire assemblyis roughly 1½″ square and the total volume of the sample taken is aknown pre-set amount of approximately 1 cubic centimeter.

The sampling piston (101) is generally operated between the two fixedmechanical stops (103) and (105) to maximize the repeat accuracy of thepump stroke in pulling in a sample of fixed size. In the down positionas shown in FIG. 2A, the piston (101) face (and thus the diaphragm(121)) will generally nearly touch the fuel cell (135) face so as tominimize the amount of ambient air in the gas reaction chamber (133).The piston (101) will generally only travel approximately 0.07 inchesbetween the down and the up position. Prior experiments have generallyindicated that the sample volume taken in is repeatable and consistentwith a less than 0.3% change between sample sizes providing a high levelof accuracy in determining the alcohol present in the larger “breath”from which the sample is taken.

In the embodiment of FIGS. 1-3, the sampling inlet (131) generallyprotrudes into a manifold (605) of flowing gas from which it withdrawsthe sample for analysis, as is generally shown in FIG. 6. The flowinggas may be human breath in the case of an alcohol breath test or itmight be either a wet or dry gas standard for instrument calibration oraccuracy check. Generally, the manifold (605) will comprise a sealedpathway which is designed concentrate the breath into a flowing streamfor testing purposes. In order to make sure that a good sample iscollected from a human using the breath tester, the stream thereforeincludes significantly more gas than will be pulled into the reactionchamber (133). Thus, the amount of gas which is fed into the manifold(605) is vastly greater than the amount of gas put into the reactionchamber (133). This gas is exhausted out the end of the manifold (605)to the ambient air at a level hundreds of times greater than the smallamount which is actually brought into the reaction chamber (133) foranalysis.

With reference to the fuel cell sampler shown in FIGS. 1-3 andparticularly FIG. 3, FIG. 4 shows a first embodiment illustrating how atest sample of material may be provided on demand. Specifically, in theembodiment of FIG. 4 the piston (101) and thus the diaphragm (121) areplaced in the UP position of FIG. 2C. This may be obtained by placingthe device in a calibration mode where the reaction chamber is adjustedbut no sample, or simply a sample of ambient air, is pulled into thereaction chamber (133) from the inlet. Droplets (401) of alcohol and/orany other liquid (407) are fed directly and on demand to the reactionchamber (133) from a holding vessel (403) through a dispensing head(405).

The dispensing head (405) is designed to provide for a number of evenlysized droplets of liquid. Specifically, the drops (401) will be of aspecific predetermined size and the action of supplying them will resultin a specific number of drops (401) being provided. In anotherembodiment, the number of drops (401) is counted by a monitoring system(419) to determine the number dispensed in this test. Thus, anyvariation in the specific number between tests can be determined. Themonitoring system (419) may comprise any system or means known to one ofordinary skill in the art for determining the number of droplets (401)dispensed including but not limited to microprocessor controls, hardwired circuits, or hardware counting mechanisms. Consequently, theautomatic instrument calibrations and accuracy checks performed by thebreath tester (100) will be highly accurate and require a much smalleramount of calibration material to be used per test. Firstly, there is nogas wasted in such an embodiment as all liquid material (407) isinjected directly into the reaction chamber (133) which had alreadytaken in the necessary “carrier” gas by being moved into the position ofFIG. 2C. Secondly, the amount of alcohol injected with each test can bedetermined to a high degree of accuracy.

In an alternative embodiment, the liquid may be injected into thereaction chamber (133) while the piston (101) is in the position of FIG.2A where the reaction chamber is much smaller but remains still and isfilled with a “carrier” gas (generally air) which is in an ambientstate. In either embodiment, gas (and carried liquid) is not exhaustedto ambient during calibration. Since the injected material is alcohol oralcohol and water, the standard source can be continually supplied atlow cost. The vessel (403) may be provided in a sealed or refillableform internal to the encasement of the device and thus is available atany time and at any location. Thus the device may be calibrated and/ortested for accuracy at any time. Further, since the liquid (407) isdirectly injected into the reaction chamber (133), there is virtually nopossibility of condensation in the air path, and therefore theconcentration is clear, repeatable and determinable.

To provide for the concentration to be fixed, it is desirable to be ableto control two features of the dispensing head's (405) dispensation.Specifically drops (401) are to be of a known size (so each includes aknown amount of liquid) and the number of drops (401) dispensed needs tobe determinable for each test. In an embodiment, those facets of thedroplets (401) are determined by using a nozzle (415) for dispensing inconjunction with a means (417) for inducing capillary waves on theliquid (407). In order to induce the capillary waves on the fluiddroplets (401), a wide variety of methods and means may be used. Theseinclude, but not limited to, piezo-type or resistive heating deviceswhich can be used for such purpose as is known to those of ordinaryskill in the art. Specifically, these devices will generally cause theliquid (407) to be ejected from the nozzle (415) in a jet of known (andconsistent) sized droplets (401). Depending on the specific design ofthe inducement device (417) and nozzle (405), the drop (401) sizes ofthe liquid (407) may vary, as might the rate of production of the drops.So as to insure that the specifically desired amount is dispensed, thebreath tester (100) may also include an electronic control or monitoringsystem (419) which will seek to provide a certain number of certainsized drops (401) to be dispensed on demand.

The combination of the number of drops (which is the total volume ofcalibration gas and/or aerosol supplied) (401) and the concentration ofthe alcohol in the liquid (407) will determine what amount of alcoholpresented to the fuel cell (135) for reaction. This can be madeequivalent to the same amount of alcohol that might be introduced bytaking a 1 cc sample of a wet or dry gas standard of the prior art ormay comprise a different amount for different calibration or accuracychecking purposes.

In an embodiment, the monitoring system (419) may have the capability tovary the number of drops (401) on demand (such as by determining howmany individual drops are formed). In this embodiment various equivalentstandards might be presented to the fuel cell (135), performing, forexample, an automatic linearity test to make sure that the breath tester(100) is accurately determining a range of values. Because some users ofbreath testers will find it beneficial to perform accuracy andcalibration tests at more than one gas concentration, this not onlyallows for the breath tester calibration to be performed wherever andwhenever is needed, but can allow for a variety of tests to be performedat the same time.

The vessel (403) may contain pure alcohol but in the depicted embodimentit does not contain pure alcohol, but includes a known concentration ofalcohol mixed with water and/or other liquids commonly found in humanbreath. Pure alcohol is extremely hygroscopic and therefore difficult tohandle without it immediately taking on water. A mixture with water ismore stable and therefore can provide for easier and longer term storageof the breath tester. Also, the more dilute the alcohol/water mixtureis, the more drops (401) will be required per calibration sampleresulting in larger samples needing to be produced for the sameconcentration. Up until a limit, a larger sample will generally make thesystem more accurate as a delivery error of one drop will have far lesseffect on the total alcohol delivered if the alcohol has been heavilydiluted with water.

The dispensing head (405) would generally inject the alcohol, water, orother liquid at a calculated rate that would provide a specificconcentration of one or more substances such as, but not limited to,ethanol; ethanol & water; methanol; or methanol & ethanol & water. Theseare just a few examples of liquids (407) or combination of liquids (407)that could be injected into the reaction chamber (133) and can be storedin the vessel (403). There could be one or many heads (405), each withtheir own vessel (403) of liquid (407). The liquid (407) in multiplevessels (403) could be duplicative, so as to provide for possibleindependent verifications of any reading from any one vessel (403), orcould include different materials so as to provide for different tests.

In an embodiment, the different liquids (407) could be used to providefor different types of testing. For example, the testing could be todetect specific interfering substances. That is, the different heads(405) could provide the same sample sizes, but using different mixtures(407). Alternatively, the different heads (405) could produce differentsample sizes with different mixtures (407). In an embodiment, this wouldprovide for a further accuracy check as the same net alcohol amountcould be provided in two different samples. One sample could be asmaller amount of a higher concentration, and the other a larger amountof a lower concentration. If the breath tester (100) read both samplesidentically and accurately, its calibration could be further confirmed.

Depending on the exact head (405) technology and instrument design, thereservoir (403) may need to be heated to keep the mixture (407) at aknown density. It might also need to be vented in some fashion. In anembodiment, this venting could comprise a one-way check valve to alwaysequalize pressure in the vessel (403) with ambient pressure.Alternatively, a pressure may be applied to the reservoir (403) as itempties so as to maintain the mixture (407) at a constant determinablestate. In order to maintain such a pressure, or simply to determine howfull the reservoir (403) is, sensors may be associated with thereservoir (403). In an embodiment, such sensors can also be used todetermine orientation of the vessel (403), and therefore make sure thata correct fluid amount is fed to the head (405) in each test as well asto determine the fill level and equalize the pressure and/or notify auser that the vessel (403) needs refilling.

Depending on a variety of design factors, the drops (401) may bedelivered to the reaction chamber (133) as tiny drops of liquid thatattach to the fuel cell (135) in liquid form or they may almostinstantaneously transform to vapor as they exit the head (405) and beessentially delivered to the reaction chamber (133) as a vapor inconjunction with air or other gas being present.

The generally preferred design will include little or no dead spacebetween the nozzle (415) exit and the reaction chamber (133) so as toprevent drops (401) from contacting or adhering to any form of carriercomponent. In this way, drops (401) are not lost in transit but alldrops (401) created by the head (405) make it to the reaction chamber(133). There are a variety of ways the head (405) can be orientedcompared to the fuel cell (135) surface and while the embodiment of FIG.4 shows it being arranged at the side, this is by no means required.There may be advantages to one orientation or another specifically toprovide for reservoir (403) being positioned within the housing of thebreath tester (100) which will generally depend on the type of breathtester (100) being used and the relative positioning of the components.

The principles and embodiments discussed herein could be used for avariety of sensors besides fuel cells as the sample providing mechanismand method is independent of the type of sensor it is used with. Sensorsthat require much larger volumes of calibration gas (flowing orquiescent) may require that the head (405) further include a gas feederwhether as a part of the fluid feed or as a separate feed. Further, thedesigns, embodiments, and principles discussed here can be used inapplications beyond breath alcohol testing, including withoutlimitation, providing calibration for other mechanical “sniffer” deviceswhich are designed to sample gases and detect small concentrations ofliquid materials therein.

It is well known that the biggest cause of fuel cell (135) aging, whereaging means both calibration drift and increasingly longer time to givea result, is the loss of water content in the fuel cell (135) material.Specifically, the cell (135) will dry out over time and have much moretrouble reading. The systems and methods described herein could also beeasily used to automatically inject liquid into the reaction chamber(133), and thus to the fuel cell (135) from time to time to keep thefuel cell (135) hydrated. In such an embodiment, it is preferred thatthere be a second vessel (403) having only water therein so as toprevent an inaccurate reading from alcohol being left sitting in thereaction chamber (133). The pure water head (405) could then be used tore-hydrate the fuel cell (133) either on-demand or according to anautomated schedule.

Dispensing systems such as those contemplated above could also be usedfor applying other reference chemicals to the sensor (135) to facilitatethe detection of “interfering substances” or calibrating the detectionof such substances. Those skilled in the art understand that sensorsmight have cross-sensitivity to compounds that might be expected in thebreath, the presence of which could result in the breath tester (100)producing an inaccurate result. The ability to calibrate the breathtester (100) to deal with the presence of such substances can furtherincrease its accuracy.

The vessel (407) and dispensing head (405) contemplated herein wouldgenerally be significantly smaller than a dry gas tank or a wetsimulator, thus making it advantageous for use in portable as well asfixed-location equipment. Furthermore, the power required to operatethis apparatus would be much less than that required to operate a wetbath Simulator (which typically requires heaters and stirrer motors) aswell as being significantly easier to use and more stable. As mentionedabove, these systems do not require high pressure gas to be stored, thusremoving a safety concern with dry gas standards. Further, it is highlylikely that such a system could be enclosed in the same housing as theremaining components of the breath alcohol tester (100) and thus wouldbe highly convenient for use at any time.

Those skilled in the art understand that some breath tester governingauthorities require use of “external” standards for calibration andaccuracy checks. Some authorities might not consider this system as an“external” standard completely independent of the instrument since thehead (405) and vessel (403) are designed to interact directly with thereaction chamber (133). While the dispensing system is exterior to theoperational parts of the instrument (that is external to the reactionchamber (133)), the vessel (403) and head (405) may be arranged internalto the housing of the breath tester (100) and thus be “internal” to theinstrument. While external standards may be required in some instances,there is also a history of using “internal” standards in some instances,situations, and jurisdictions. These are routinely used in the field asaccuracy checks, even though external standards may be required forformal calibrations to provide for improved certainty of results.

While the above embodiment contemplates use of the liquid jet without acarrier gas being used, the principles, systems, and methods discussedabove may also be used in an embodiment with a carrier gas, such as inthe embodiment of FIG. 5. This embodiment could be used as an internalstandard but would more likely be used as an external standard such asmay be required to meet such regulations on testing. This embodiment isnot meant to be separate from the principles, systems, and methodsdiscussed above, but builds on, the above description as well as usingsome or all of its aspects as described above.

In an embodiment a carrier gas (511) is utilized (so as to be anexternal standard). The carrier gas (511) is generally air, but theembodiment does not mean to rule out other carrier gases and nitrogen orother carrier gases could be used in alternative embodiments. The aircould be conditioned air that is heated, dehumidified, or exposed tosome other conditioning by an air conditioning system (505) prior tohaving the ethanol and/or water injected therein to make sure it hasexpected properties.

In one embodiment, the air would be supplied, presumably by a pump(503), at a constant flow rate from the ambient (501) to eliminate theneed for a compressed tank. However, other methods that provide aconstant flow rate or constant mass flow rate could be used. Forexample, regulated delivery from a pressurized tank of carrier gas (511)could be used. In a still further embodiment, a pump (503) could be usedto present an approximately known flow rate and a mass flow sensor orflow sensor could be used to measure the exact mass flow rate or flowrate in order to calculate the exact rate the dispensing system shoulddeliver drops in order to produce a precise and desired concentration. Asimilar feedback system could be used with pressurized carrier gas aswell.

Heads (405) would inject the alcohol (507), water (509), or other liquidat a calculated rate that, in conjunction with the flow of carrier gas(511), would provide a specific concentration of one or more substancessuch as, but not limited to, ethanol; ethanol & water; methanol; ormethanol & ethanol & water into the carrier gas stream (511). As in thedepicted embodiment, there could be one or many dispensing heads (405),each with their own reservoir of liquid to provide for independentmixing as the material is provided to the carrier gas (511), or thevarious dispensing heads (405) may be provided with premixed samples. Inthe latter embodiment, fewer heads (405) will generally be required,which can simplify the system; however, providing for more specificalternative concentrations can be more difficult. The liquid (507) or(509) in multiple reservoirs could be duplicative or each could bedifferent depending on the desired outcome.

In the embodiment where different fluids are each provided with theirown dispensing head (405), the different liquids could be added atdifferent rates at different times to provide a variety of vaporconcentrations. Further, the rates of injection could be varied in realtime in order to provide a profile over time of changing concentrationsof one or more substances in the carrier gas (511).

While the carrier gas (511) and fluid mixture may be provided to thebreath tester (517) at this point, it may be required, in someembodiments, that the substance be carried as a vapor in the carrier gas(511) and not as an aerosol which may be produced by the dispensing head(405). Some turbulence may, therefore, need to be added to the flow inorder to produce complete homogeneity of the mixture. In the embodimentof FIG. 5 the output carrier gas (511) with the fluid therein is fedinto a homogenizer (513) so as to provide a more homogenized carriergas/fluid mixture (515) (that is, a vapor) which is then provided to thebreath tester (517). Other conditioning of the flow may be required suchas heating or pressure change in order to produce homogeneity of themixture (515) which may be performed by the homogenizer (513).

To use the output carrier gas (515) of the embodiment of FIG. 5, thecarrier gas (515) (and thus the carried liquid) may be provided to abreath tester by variety of different methodologies. In FIG. 6 there isshown a breath tester (601) which takes a discrete small sample foranalysis at an instant in time during a human subject's exhalation. Thistype of tester (601) typically includes a sampling port (603) with inlet(131) that protrudes into a mouthpiece or manifold (605) of flowing gas.The manifold (605) may be a permanent part of the breath tester (601) ormay be a temporary manifold such as a disposable mouthpiece (605)temporarily mounted on a breath tester's sampling port (603). In a stillfurther embodiment, the manifold (605) could be a part of a testingsystem that temporarily connects to the breath tester (601) such as toreplace such a disposable mouth piece (605). In this embodiment, theflowing gas (607) into the manifold (605) of whatever description couldbe a designed concentration of a known vapor in a carrier gas (515) aswould be produced in FIG. 5. As this carrier gas (515) is passed throughthe manifold, the breath tester (601) will obtain a sample through theinlet port (603) and (131) in the standard fashion. The gas which is notutilized is then exhausted (609) from the manifold (605).

A second type of Breath Tester (701) makes a continuous analysis in realtime during a human subject's exhalation and an example is shown in FIG.7. This tester (701) typically includes a measurement chamber (703)through which all the flowing gas (707) passes through. There isconnecting tubing (705) which directs the gas (707) into and out of(709) the chamber (703). In the chamber (703) a measurement system suchas one utilizing an infrared source (711) and detector (713) can then beused. In this embodiment, the carrier gas (707) can be continuouslyprovided having either a fixed concentration or a varying concentrationof known variance to provide for the carrier gas (707) to be tested inthe chamber (703).

While the invention has been disclosed in connection with certainpreferred embodiments, this should not be taken as a limitation to allof the provided details. Modifications and variations of the describedembodiments may be made without departing from the spirit and scope ofthe invention, and other embodiments should be understood to beencompassed in the present disclosure as would be understood by those ofordinary skill in the art.

1. A calibration system for a breath tester comprising: a storagereservoir containing a mixture of water and an alcohol at knownconcentration; a dispensing head for dispensing said mixture, saiddispensing head including a nozzle for ejecting said mixture from saidstorage reservoir; wherein said dispensing head injects said mixturedirectly into a reaction chamber of said breath tester.
 2. The system ofclaim 1 wherein said alcohol comprises ethanol.
 3. The system of claim 1wherein said alcohol comprises methanol.
 4. The system of claim 1wherein said mixture also comprises an interfering substance.
 5. Thesystem of claim 1 wherein said dispensing head dispenses said mixtureinto a carrier gas.